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  Select top 3 values from each group in a table with SQL

Yesterday, my friend Liu Bing asked me a question about how to select top 3 values for each person in a database table using SQL. I think this question is interesting and it deserves some thoughts. Here I record down how to solve this issue. Assume we have a table which has two columns, one column contains the names of some people and the other column contains some values related to each person. One person can have more than one value. Each value has a numeric type. The question is we want to se...

   SQL,Correlated query,top 3     2013-05-23 03:21:25

  Becoming a Better Developer, Part 1: Making Fans

If you're trying to grow your startup you've come to the right place. Get my 170-page ebook on how to grow a startup and join thousands of self-funded entrepreneurs by subscribing to my newsletter at right. This is the first of what I hope to become an ongoing series about non-technical ways to improve yourself as a developer. Becoming a better developer involves more than learning new technical skills; learning about your company and co-workers will dramatically improve the software y...

   Developer,Tips     2011-06-29 08:38:26

  Generate first N prime numbers

Recently I am taking an online course named "Startup Engineering" on coursera. There is one assignment which is to use NodeJS to write a program to generate the first 100 prime numbers. This may be very easy for many people. Here I just want to share with you the code to generate not only the first 100 prime numbers. but also any number of prime numbers. Below is the code snippet: //Helper class to generate prime numbers var PrimeProcessor=(function(){ var primeArray=[]; functio...

   Algorithm,Prime number,NodeJS,coursera,JavaScript     2013-06-29 22:08:22

  Removing duplicates in sql

In modern web development, it’s standard practice to make use of a database abstraction layer, typically an Object-Relational Mapper based on either the Active Record pattern or the Data Mapper pattern. There are several pros and cons to this which are fairly well established, so I’ll spare us all from enumerating them all right now. One established pro worth mentioning is that these systems typically provide a high level interface for fetching data, often removing the need to ...

   SQL,Duplicate,Remove,Web design     2012-01-05 08:20:13

  Clojure & Java Interop

About a year ago I got a phone call asking if I wanted to join another team at DRW. The team supports a (primarily) Java application, but the performance requirements would also allow it to be written in a higher level language. I'd been writing Clojure (basically) full-time at that point - so my response was simple: I'd love to join, but I'm going to want to do future development using Clojure. A year later we still have plenty of Java, but the vast majority of the new code I add is Cloj...

   Java,Clojure,Interoprability,Commit,Function call     2011-12-29 09:11:22

  Advice on improving your programming skills

Programming is cool. But behind the scenes it's also difficult for many people. Many people are defeated at the early stage of learning programming. When you are not so familiar with programming, you may find you don't know where to start and what to start with first and where to apply the knowledge. Once you go though the tough period of the learning phase, you will find a whole new world. Below are some advice which can help you improve your programming skills quickly. Write more code.  T...

   Programming,Advice     2014-02-21 08:59:04

  Python basics summary

Python is recommended by many people as the first language to be learned now. Even in some universities, it is the primary language to be taught to CS/CE students. To master this languages, we should understand some basics of it. Here we summarize some basics about this language. These basics include : string replacement with regular expression, traverse a directory, sort a list, remove duplication, dictionary ordering, dictionary, list, string conversion, date object manipulation, command line ...

   Python,Summary     2013-09-23 10:04:42

  Python Performance Tips, Part 1

To read the Zen of Python, type import this in your Python interpreter. A sharp reader new to Python will notice the word “interpreter”, and realize that Python is another scripting language. “It must be slow!” No question about it: Python program does not run as fast or efficiently as compiled languages. Even Python advocates will tell you performance is the area that Python is not good for. However, YouTube has proven Python is capable of serving 40 million videos...

   Python,Performance,Efficiency,Tips     2012-02-14 10:50:22

  Embrace open source

In past few days, there are many tech news which are related to open source. For example, Microsoft enables Linux on its Windows Azure cloud, Facebook open sourced its C++ library Folly and Samsung joined Linux foundation. Now more and more big companies realize the power of open source and are willing to contribute to the open source community. It will benefit not only developers but also these big companies as well.By providing some open source libraries or projects, developer may reduce their...

   Open source,Microsoft,Samsung,Facebook,Linux     2012-06-06 05:37:59

  The requirements of DevOps development

DevOps has become a popular and commonly adopted software development model in IT industry in recent years. Its popularity is partially because it advocates it could improve software development efficiency, delivery speed and cost saving. This is especially favored by managers who become the main force to promote this type of development model in their companies. However, we must be cautious about DevOps model as well. With their advantages, they also bring challenges to development teams and th...

   AGILE,DEVOPS,SPRINT     2018-06-03 23:18:44

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